Variable length codeword decoders (VLD's) are known in the art of signal transmission, and are implemented to decode variable length encoded signals. Variable length encoded signals are generated in pulse code modulated form, and respective codewords are concatenated without flags to distinguish successive codewords. Respective codewords may be formed with differing numbers of bits. Respective codewords include a prefix part and a data part. The prefix is utilized to facilitate separation of concatenated variable length codewords, and in general, is indicative of the number of bits comprising the particular codeword.
Typically, known VLD's include a lookup table to which successive bits of a variable length encoded signal are sequentially and cumulataively applied as address codes. When a sequence of bits applied to the address input port of the lookup table conforms to a valid variable length codeword, the lookup table provides a decoded representation of the variable length codeword, and a value representing the length of the variable length codeword. Responsive to the value representing the length of the variable length codeword, the decoded variable length codeword is stripped from the signal applied to the lookup table and the process is repeated.
One of the limiting factors in the operational speed of known VLD's is the rate of application of new codewords to the decoder lookup table. The present invention provides a novel circuit arrangement for arranging coded data for application to the address port of a VLD lookup table.